A novel panel of mouse models to evaluate the role of human pregnane X receptor and constitutive androstane receptor in drug response
Nico Scheer, Jillian Ross, Anja Rode, Branko Zevnik, Sandra Niehaves, Nicole Faust, C. Roland Wolf
Nico Scheer, Jillian Ross, Anja Rode, Branko Zevnik, Sandra Niehaves, Nicole Faust, C. Roland Wolf
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Technical Advance Metabolism

A novel panel of mouse models to evaluate the role of human pregnane X receptor and constitutive androstane receptor in drug response

Abstract

The pregnane X receptor (PXR) and the constitutive androstane receptor (CAR) are closely related orphan nuclear hormone receptors that play a critical role as xenobiotic sensors in mammals. Both receptors regulate the expression of genes involved in the biotransformation of chemicals in a ligand-dependent manner. As the ligand specificity of PXR and CAR have diverged between species, the prediction of in vivo PXR and CAR interactions with a drug are difficult to extrapolate from animals to humans. We report the development of what we believe are novel PXR- and CAR-humanized mice, generated using a knockin strategy, and Pxr- and Car-KO mice as well as a panel of mice including all possible combinations of these genetic alterations. The expression of human CAR and PXR was in the predicted tissues at physiological levels, and splice variants of both human receptors were expressed. The panel of mice will allow the dissection of the crosstalk between PXR and CAR in the response to different drugs. To demonstrate the utility of this panel of mice, we used the mice to show that the in vivo induction of Cyp3a11 and Cyp2b10 by phenobarbital was only mediated by CAR, although this compound is described as a PXR and CAR activator in vitro. This panel of mouse models is a useful tool to evaluate the roles of CAR and PXR in drug bioavailability, toxicity, and efficacy in humans.

Authors

Nico Scheer, Jillian Ross, Anja Rode, Branko Zevnik, Sandra Niehaves, Nicole Faust, C. Roland Wolf

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Figure 9

CAR-dependent induction of Cyp2b10 and Cyp3a11 by PB.

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CAR-dependent induction of Cyp2b10 and Cyp3a11 by PB. (A) Pooled liver m...
(A) Pooled liver microsomes from huPXR, PXR KO, huCAR, CAR KO, huPXR/huCAR, PXR KO/CAR KO, huPXR/CAR KO, PXR KO/huCAR, and WT mice (n = 3) treated with either PB or vehicle were analyzed for Cyp2b10 and Cyp3a11 expression by immunoblotting. 5 μg protein was loaded onto a 7.5% SDS-PAGE gel, and membranes were incubated with polyclonal Cyp2b10 and Cyp3a11 antibodies. (B) PROD and BQ assays were performed to investigate Cyp2b and Cyp3a activities, respectively, in pooled mouse liver microsomes from each mouse line indicated above (n = 3 mice). Values are expressed as mean ± SD; n = 3 mice for all experiments. Student’s t test (2-sided) was performed. *P < 0.05; **P < 0.01; ***P < 0.001, statistically different from control.